searching for a specific line in a text file

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February 11th, 2004, 05:28 AM

mattcronin57

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searching for a specific line in a text file

hi,

im trying to rewrite a perl script i have in python. the script just checks that certain directories exist.

i have a configuration file that lists the directories to be checked, like this:

dir:/path/to/wherever:/another/path:/yet/another

however, i can't figure out how to find and read this line only. i have tried to do it in the following way but it doesn't seem to find anything:

confFile = open('/home/me/file.conf', "r").read()
for line in confFile:
if line[0] == "dir:":
print line,

please help, this is driving me mad, as i can't seem to find any relevant docs anywhere

February 11th, 2004, 06:35 AM

netytan

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The problem is that file.read() is a string

, so when you loop over this you're actually iterating over each letter. not a line, so you're condition will never be True.

What you actually want is something like this.

Code:

#!/usr/bin/env python

import os

for line in file('paths.txt', 'r'):
	if line.startswith('dir:'):
		paths = line[4:].split(':')

		for path in paths:
			if os.path.exists(path): print path,

What this does is iterate over the file instance (line by line) and finds any lines beginning with 'dir:'. Then splits this line slice so we have a bunch of path. Loop over them and check if they exists. If they do then we print the path!

Hope this helps clear things up,

Mark.

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February 11th, 2004, 06:41 AM

netytan

Hello World :)

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While i think about it this would break using absolute paths since C:/whatever/ would be come ['C', '/whatever/']. Maybe you could post you're perl version

i wouldn't mind seeing it if only out of interested .

Mark.

February 11th, 2004, 06:45 AM

Grim Archon

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Almost there

Code:

confFile = open('/home/me/file.conf', "r").readlines()
#confile is now a list of lines as strings ["line1","line2", ....]
for line in confFile: #try one line at a time
    if line.find("dir:") == 0: #using string methods search for 'dir:'. find returns the sub-string position (it returns -1 if not found)
        print line,

Grim

February 11th, 2004, 07:26 AM

mattcronin57

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thanks for the help

thanks for the help both of you, i used a mixture of both your replys to get it working.

netytan, although i don't need you to help me with anything more, here is the perl snippet for your curiosity:

if (open CONF, "</home/me/file.conf") {
select CONF;
while (<CONF>) {
chomp;
if (/^dir:/) {
@directories = split /:/, $_;
shift @directories;
foreach (@directories) { print "$_ \n" }
}
}
}

February 11th, 2004, 07:35 AM